SFP (Small Form-Factor Pluggable) plus transceiver or SFP+ module is a next-generation, hot-pluggable, small-footprint, serial-to-serial, multi-rate optical transceiver for 8.5GbE to 11GbE data communications and storage-area network (SAN) applications. The SFP+ module is turned out to be the highest density and lowest cost option for 10-Gigabit Ethernet optical links, with the tradeoff of more high-speed design work up front for the host-card designer.
SFP+ is upgraded from SFP transceiver(or mini GBIC), but what are the improved aspects of SFP+ compared with former fiber optic modules like XENPAK, GBIC, XFP, X2? As you know, SFP+ module has the advantages of smaller, lower cost and more efficient.
The SFP+ module form factor is 30% smaller, uses less power, requires fewer components, which was already smaller and used less power than the XAUI-based XENPAK and X2 form factors.
SFP+ optical transceiver is able to offer significantly lower cost than the existing modules. The SFP+ is not a magic bullet for 10-Gigabit Ethernet conversion; innovation in optics, silicon, and module design continue to move optical transceivers down the cost curve. What the architecture choice can do is help 10-Gbit/sec get on the right curve-in this case, the same types of cost and volume curves as Gigabit Ethernet.
The SFP+ module enhances the mechanical form factor of the SFP to add improved signal integrity and EMI shielding appropriate to higher data rates, and defines new electrical interface specifications.
The SFP+ form factor significantly simplifies the functionality of the 10G optical module by moving such functions as clock and data recovery (CDR), electronic dispersion compensation (EDC), 10G SERDES, and signal conditioning that traditionally resided inside the XAUI-based modules into 10GbE PHY devices and line cards. As a result, the modules are smaller, consume less power, and allow increased port density while being less expensive than XFP. Some products on the market now offer 48 ports or more in a rack.
Challenges SFP+ Transceivers Meet
While SFP+ significantly simplifies the functionality of the 10G optical module, it introduces a number of new test and measurement challenges. The increased port density afforded by SFP+ drives the need for automation to speed the test of 48 or more ports per rack. Other challenges include the need to move seamlessly from compliance testing to debug testing, the need for specialized test fixtures, and the use of real-time oscilloscopes compared to equivalent-time oscilloscopes.
The Current Situation Of The Mainstream Modules
Several different optical transceiver form factors compete for 10-Gbit/sec applications, each with its own advantages and disadvantages. The XENPAK and X2 module form factors are shipping in volume today and are the most mature 10-Gbit/sec approaches. They support all required reaches, and their four-lane XAUI electrical interface eliminates the need for very high-speed design on the host card. The XFP form factor enables higher densities, supports most reaches, and typically costs less than the XENPAK and X2.
The SFP+ high-density, low-cost optical transceiver should help enable the 10-Gigabit Ethernet transition in enterprise networks by meeting a variety of customer demands. The SFP+ module offers simpler, higher-density host card architectures than other modules can support, which is expected to be the “end game” optical transceiver for 10 Gigabit Ethernet.